Basically the main answer is They adapt to their environment
<span> solids have more Compact Structure.
fluids have l</span><span>ess Compact Structure.</span>
it is categorized by three types
1. igneous rock
2. sedimentary rock
3. metamorphic rock
In lieu with your question, only 10% marine life are adapted to withstand the immense hydro-static pressure below 180 meters. Other 90% are adapted to live in surface of ocean or on their evolutionary way to land.
The right answer is B) crossing over.
Crossing-over is a genetic phenomenon that occurs during meiosis and contributes to genetic mixing during reproduction (genetic recombination).
At the end of prophase 1 (early metaphase 1) of meiosis, the homologous chromosomes (i.e. of the same pair) overlap thus forming characteristic features called "chromatid tetrads" and exchange fragments of chromatids. The result is the intra-chromosomal mixing of the alleles
